* [including the GNU Public Licence.]
*/
+#define OPENSSL_FIPSAPI
+
#include <stdio.h>
#include <openssl/bn.h>
#include "cryptlib.h"
/* The next 2 are needed so we can do a dv->d[0]|=1 later
* since BN_lshift1 will only work once there is a value :-) */
BN_zero(dv);
- bn_wexpand(dv,1);
+ if(bn_wexpand(dv,1) == NULL) goto end;
dv->top=1;
if (!BN_lshift(D,D,nm-nd)) goto end;
*
* <appro@fy.chalmers.se>
*/
+#undef bn_div_words
# define bn_div_words(n0,n1,d0) \
({ asm volatile ( \
"divl %4" \
* Same story here, but it's 128-bit by 64-bit division. Wow!
* <appro@fy.chalmers.se>
*/
+# undef bn_div_words
# define bn_div_words(n0,n1,d0) \
({ asm volatile ( \
"divq %4" \
#endif /* OPENSSL_NO_ASM */
-/* BN_div[_no_branch] computes dv := num / divisor, rounding towards
+/* BN_div computes dv := num / divisor, rounding towards
* zero, and sets up rm such that dv*divisor + rm = num holds.
* Thus:
* dv->neg == num->neg ^ divisor->neg (unless the result is zero)
* rm->neg == num->neg (unless the remainder is zero)
* If 'dv' or 'rm' is NULL, the respective value is not returned.
*/
-static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,
- const BIGNUM *divisor, BN_CTX *ctx);
int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
BN_CTX *ctx)
{
BN_ULONG *resp,*wnump;
BN_ULONG d0,d1;
int num_n,div_n;
+ int no_branch=0;
/* Invalid zero-padding would have particularly bad consequences
* in the case of 'num', so don't just rely on bn_check_top() for this one
if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0))
{
- return BN_div_no_branch(dv, rm, num, divisor, ctx);
+ no_branch=1;
}
bn_check_top(dv);
return(0);
}
- if (BN_ucmp(num,divisor) < 0)
+ if (!no_branch && BN_ucmp(num,divisor) < 0)
{
if (rm != NULL)
{ if (BN_copy(rm,num) == NULL) return(0); }
if (dv == NULL)
res=BN_CTX_get(ctx);
else res=dv;
- if (sdiv == NULL || res == NULL) goto err;
+ if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL)
+ goto err;
/* First we normalise the numbers */
norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
norm_shift+=BN_BITS2;
if (!(BN_lshift(snum,num,norm_shift))) goto err;
snum->neg=0;
- div_n=sdiv->top;
- num_n=snum->top;
- loop=num_n-div_n;
- /* Lets setup a 'window' into snum
- * This is the part that corresponds to the current
- * 'area' being divided */
- wnum.neg = 0;
- wnum.d = &(snum->d[loop]);
- wnum.top = div_n;
- /* only needed when BN_ucmp messes up the values between top and max */
- wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */
- /* Get the top 2 words of sdiv */
- /* div_n=sdiv->top; */
- d0=sdiv->d[div_n-1];
- d1=(div_n == 1)?0:sdiv->d[div_n-2];
-
- /* pointer to the 'top' of snum */
- wnump= &(snum->d[num_n-1]);
-
- /* Setup to 'res' */
- res->neg= (num->neg^divisor->neg);
- if (!bn_wexpand(res,(loop+1))) goto err;
- res->top=loop;
- resp= &(res->d[loop-1]);
-
- /* space for temp */
- if (!bn_wexpand(tmp,(div_n+1))) goto err;
-
- if (BN_ucmp(&wnum,sdiv) >= 0)
+ if (no_branch)
{
- /* If BN_DEBUG_RAND is defined BN_ucmp changes (via
- * bn_pollute) the const bignum arguments =>
- * clean the values between top and max again */
- bn_clear_top2max(&wnum);
- bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
- *resp=1;
- }
- else
- res->top--;
- /* if res->top == 0 then clear the neg value otherwise decrease
- * the resp pointer */
- if (res->top == 0)
- res->neg = 0;
- else
- resp--;
-
- for (i=0; i<loop-1; i++, wnump--, resp--)
- {
- BN_ULONG q,l0;
- /* the first part of the loop uses the top two words of
- * snum and sdiv to calculate a BN_ULONG q such that
- * | wnum - sdiv * q | < sdiv */
-#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
- BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
- q=bn_div_3_words(wnump,d1,d0);
-#else
- BN_ULONG n0,n1,rem=0;
-
- n0=wnump[0];
- n1=wnump[-1];
- if (n0 == d0)
- q=BN_MASK2;
- else /* n0 < d0 */
- {
-#ifdef BN_LLONG
- BN_ULLONG t2;
-
-#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
- q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
-#else
- q=bn_div_words(n0,n1,d0);
-#ifdef BN_DEBUG_LEVITTE
- fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
-X) -> 0x%08X\n",
- n0, n1, d0, q);
-#endif
-#endif
-
-#ifndef REMAINDER_IS_ALREADY_CALCULATED
- /*
- * rem doesn't have to be BN_ULLONG. The least we
- * know it's less that d0, isn't it?
- */
- rem=(n1-q*d0)&BN_MASK2;
-#endif
- t2=(BN_ULLONG)d1*q;
-
- for (;;)
- {
- if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)|wnump[-2]))
- break;
- q--;
- rem += d0;
- if (rem < d0) break; /* don't let rem overflow */
- t2 -= d1;
- }
-#else /* !BN_LLONG */
- BN_ULONG t2l,t2h;
-
- q=bn_div_words(n0,n1,d0);
-#ifdef BN_DEBUG_LEVITTE
- fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
-X) -> 0x%08X\n",
- n0, n1, d0, q);
-#endif
-#ifndef REMAINDER_IS_ALREADY_CALCULATED
- rem=(n1-q*d0)&BN_MASK2;
-#endif
-
-#if defined(BN_UMULT_LOHI)
- BN_UMULT_LOHI(t2l,t2h,d1,q);
-#elif defined(BN_UMULT_HIGH)
- t2l = d1 * q;
- t2h = BN_UMULT_HIGH(d1,q);
-#else
+ /* Since we don't know whether snum is larger than sdiv,
+ * we pad snum with enough zeroes without changing its
+ * value.
+ */
+ if (snum->top <= sdiv->top+1)
{
- BN_ULONG ql, qh;
- t2l=LBITS(d1); t2h=HBITS(d1);
- ql =LBITS(q); qh =HBITS(q);
- mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
+ if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err;
+ for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0;
+ snum->top = sdiv->top + 2;
}
-#endif
-
- for (;;)
- {
- if ((t2h < rem) ||
- ((t2h == rem) && (t2l <= wnump[-2])))
- break;
- q--;
- rem += d0;
- if (rem < d0) break; /* don't let rem overflow */
- if (t2l < d1) t2h--; t2l -= d1;
- }
-#endif /* !BN_LLONG */
- }
-#endif /* !BN_DIV3W */
-
- l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
- tmp->d[div_n]=l0;
- wnum.d--;
- /* ingore top values of the bignums just sub the two
- * BN_ULONG arrays with bn_sub_words */
- if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1))
+ else
{
- /* Note: As we have considered only the leading
- * two BN_ULONGs in the calculation of q, sdiv * q
- * might be greater than wnum (but then (q-1) * sdiv
- * is less or equal than wnum)
- */
- q--;
- if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
- /* we can't have an overflow here (assuming
- * that q != 0, but if q == 0 then tmp is
- * zero anyway) */
- (*wnump)++;
+ if (bn_wexpand(snum, snum->top + 1) == NULL) goto err;
+ snum->d[snum->top] = 0;
+ snum->top ++;
}
- /* store part of the result */
- *resp = q;
- }
- bn_correct_top(snum);
- if (rm != NULL)
- {
- /* Keep a copy of the neg flag in num because if rm==num
- * BN_rshift() will overwrite it.
- */
- int neg = num->neg;
- BN_rshift(rm,snum,norm_shift);
- if (!BN_is_zero(rm))
- rm->neg = neg;
- bn_check_top(rm);
- }
- BN_CTX_end(ctx);
- return(1);
-err:
- bn_check_top(rm);
- BN_CTX_end(ctx);
- return(0);
- }
-
-
-/* BN_div_no_branch is a special version of BN_div. It does not contain
- * branches that may leak sensitive information.
- */
-static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,
- const BIGNUM *divisor, BN_CTX *ctx)
- {
- int norm_shift,i,loop;
- BIGNUM *tmp,wnum,*snum,*sdiv,*res;
- BN_ULONG *resp,*wnump;
- BN_ULONG d0,d1;
- int num_n,div_n;
-
- bn_check_top(dv);
- bn_check_top(rm);
- /* bn_check_top(num); */ /* 'num' has been checked in BN_div() */
- bn_check_top(divisor);
-
- if (BN_is_zero(divisor))
- {
- BNerr(BN_F_BN_DIV_NO_BRANCH,BN_R_DIV_BY_ZERO);
- return(0);
- }
-
- BN_CTX_start(ctx);
- tmp=BN_CTX_get(ctx);
- snum=BN_CTX_get(ctx);
- sdiv=BN_CTX_get(ctx);
- if (dv == NULL)
- res=BN_CTX_get(ctx);
- else res=dv;
- if (sdiv == NULL || res == NULL) goto err;
-
- /* First we normalise the numbers */
- norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
- if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err;
- sdiv->neg=0;
- norm_shift+=BN_BITS2;
- if (!(BN_lshift(snum,num,norm_shift))) goto err;
- snum->neg=0;
-
- /* Since we don't know whether snum is larger than sdiv,
- * we pad snum with enough zeroes without changing its
- * value.
- */
- if (snum->top <= sdiv->top+1)
- {
- if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err;
- for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0;
- snum->top = sdiv->top + 2;
- }
- else
- {
- if (bn_wexpand(snum, snum->top + 1) == NULL) goto err;
- snum->d[snum->top] = 0;
- snum->top ++;
}
div_n=sdiv->top;
/* Setup to 'res' */
res->neg= (num->neg^divisor->neg);
if (!bn_wexpand(res,(loop+1))) goto err;
- res->top=loop-1;
+ res->top=loop-no_branch;
resp= &(res->d[loop-1]);
/* space for temp */
if (!bn_wexpand(tmp,(div_n+1))) goto err;
+ if (!no_branch)
+ {
+ if (BN_ucmp(&wnum,sdiv) >= 0)
+ {
+ /* If BN_DEBUG_RAND is defined BN_ucmp changes (via
+ * bn_pollute) the const bignum arguments =>
+ * clean the values between top and max again */
+ bn_clear_top2max(&wnum);
+ bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
+ *resp=1;
+ }
+ else
+ res->top--;
+ }
+
/* if res->top == 0 then clear the neg value otherwise decrease
* the resp pointer */
if (res->top == 0)
rm->neg = neg;
bn_check_top(rm);
}
- bn_correct_top(res);
+ if (no_branch) bn_correct_top(res);
BN_CTX_end(ctx);
return(1);
err:
BN_CTX_end(ctx);
return(0);
}
-
#endif
projects / openssl.git / blobdiff